/*
 * =====================================================================================
 *
 *       Filename:  node_center.cpp
 *
 *    Description:  
 *
 *        Version:  1.0
 *        Created:  2021年05月20日 11时32分55秒
 *       Revision:  none
 *       Compiler:  gcc
 *
 *         Author:  Li Chao (), lichao@aiotlink.com
 *   Organization:  
 *
 * =====================================================================================
 */
#include "node_center.h"
#include "json.h"
#include "log.h"

using ssjson::Json;

namespace
{
std::string Join(const std::string &parent, const std::string &child)
{
	return parent + kTopicSep + child;
}
const std::string kTopicCenterRoot = "#center";
const std::string kTopicNode = Join(kTopicCenterRoot, "node");
const std::string kTopicNodeOnline = Join(kTopicNode, "online");
const std::string kTopicNodeOffline = Join(kTopicNode, "offline");
} // namespace

ProcIndex ProcRecords::Put(const ProcId &proc_id, const MQId ssn)
{
	if (procs_.size() >= kMaxProcs) {
		return -1;
	}
	auto pos_isnew = proc_index_.emplace(proc_id, procs_.size());
	int index = pos_isnew.first->second;
	if (pos_isnew.second) {
		procs_.emplace_back(ProcRec{proc_id, ssn});
	} else { // update ssn
		procs_[index].ssn_ = ssn;
	}
	return index;
}
const ProcRecords::ProcRec &ProcRecords::Get(const ProcIndex index) const
{
	static ProcRec empty_rec;
	return (index < procs_.size()) ? procs_[index] : empty_rec;
}

void MsgRecords::FreeMsg(MsgId id)
{
	auto pos = msgs_.find(id);
	if (pos != msgs_.end()) {
		ShmMsg(pos->second).Free();
		msgs_.erase(pos);
	} else {
		LOG_TRACE() << "ignore late free request.";
	}
}
void MsgRecords::AutoRemove()
{
	auto now = NowSec();
	if (now < time_to_clean_) {
		return;
	}
	// LOG_FUNCTION;
	time_to_clean_ = now + 1;
	int64_t limit = std::max(10000ul, msgs_.size() / 10);
	int64_t n = 0;
	auto it = msgs_.begin();
	while (it != msgs_.end() && --limit > 0) {
		ShmMsg msg(it->second);
		auto Free = [&]() {
			msg.Free();
			it = msgs_.erase(it);
			++n;
		};
		int n = now - msg.timestamp();
		if (n < 10) {
			++it;
		} else if (msg.Count() == 0) {
			Free();
		} else if (n > 60) {
			Free();
		}
	}
	if (n > 0) {
		LOG_DEBUG() << "~~~~~~~~~~~~~~~~ auto release msgs: " << n;
	}
}

void MsgRecords::DebugPrint() const
{
	LOG_TRACE() << "msgs : " << size();
	int i = 0;
	int total_count = 0;
	for (auto &kv : msgs_) {
		MsgI msg(kv.second);
		total_count += msg.Count();
		LOG_TRACE() << "  " << i++ << ": msg id: " << kv.first << ", offset: " << kv.second << ", count: " << msg.Count() << ", size: " << msg.Size();
	}
	LOG_TRACE() << "total count: " << total_count;
}

// NodeCenter::ProcState
void NodeCenter::NodeInfo::PutOffline(const int64_t offline_time)
{
	state_.timestamp_ = NowSec() - offline_time;
	state_.flag_ = kStateOffline;

	Json json;
	json.put("proc_id", proc_.proc_id());
	center_.Publish(shm_, kTopicNodeOffline, json.dump());
}

void NodeCenter::NodeInfo::UpdateState(const int64_t now, const int64_t offline_time, const int64_t kill_time)
{
	auto old = state_.flag_;
	auto diff = now - state_.timestamp_;
	auto publish = [this](const std::string &topic) {
		if (proc_.proc_id().empty()) { return; } // node init, ignore.
		Json json;
		json.put("proc_id", proc_.proc_id());
		center_.Publish(shm_, topic, json.dump());
	};

	LOG_TRACE() << "node " << proc_.proc_id() << " timeout count: " << diff;
	if (diff < offline_time) {
		state_.flag_ = kStateNormal;
		if (old != state_.flag_) {
			publish(kTopicNodeOnline);
		}
	} else if (diff < kill_time) {
		state_.flag_ = kStateOffline;
		if (old != state_.flag_) {
			publish(kTopicNodeOffline);
		}
	} else {
		state_.flag_ = kStateKillme;
	}
}

int64_t NodeCenter::OnNodeInit(ShmSocket &socket, const int64_t val)
{
	LOG_FUNCTION;
	SharedMemory &shm = socket.shm();
	MQId ssn = (val >> 4) & MaskBits(56);
	int reply = EncodeCmd(eCmdNodeInitReply);

	if (nodes_.find(ssn) != nodes_.end()) {
		return reply; // ignore if exists.
	}

	auto UpdateRegInfo = [&](Node &node) {
		node->state_.timestamp_ = NowSec() - offline_time_;
		node->UpdateState(NowSec(), offline_time_, kill_time_);

		// create sockets.
		try {
			ShmSocket tmp(shm, true, ssn, 16);
			node->addrs_.emplace(ssn, tmp.AbsAddr());
			return true;
		} catch (...) {
			return false;
		}
	};

	auto PrepareProcInit = [&](Node &node) {
		bool r = false;
		ShmMsg init_msg;
		DEFER1(init_msg.Release());
		MsgProcInit body;
		auto head = InitMsgHead(GetType(body), id(), ssn);
		return init_msg.Make(GetAllocSize(CalcAllocIndex(900))) &&
		       init_msg.Fill(ShmMsg::Serialize(head, body)) &&
		       SendAllocMsg(socket, {ssn, node->addrs_[ssn]}, init_msg);
	};

	Node node(new NodeInfo(*this, shm));
	if (UpdateRegInfo(node) && PrepareProcInit(node)) {
		reply |= (node->addrs_[ssn] << 4);
		nodes_[ssn] = node;
		LOG_INFO() << "new node ssn (" << ssn << ") init";
	} else {
		ShmSocket::Remove(shm, ssn);
	}
	return reply;
}
void NodeCenter::RecordMsg(const MsgI &msg)
{
	msg.reset_managed(true);
	msgs_.RecordMsg(msg);
}

bool NodeCenter::SendAllocReply(ShmSocket &socket, const MQInfo &dest, const int64_t reply, const MsgI &msg)
{
	RecordMsg(msg);
	auto onExpireFree = [this, msg](const SendQ::Data &) { msgs_.FreeMsg(msg.id()); };
	return socket.Send(dest, reply, onExpireFree);
}
bool NodeCenter::SendAllocMsg(ShmSocket &socket, const MQInfo &dest, const MsgI &msg)
{
	RecordMsg(msg);
	return socket.Send(dest, msg);
}

void NodeCenter::OnAlloc(ShmSocket &socket, const int64_t val)
{
	// LOG_FUNCTION;
	// 8bit size, 4bit socket index, 16bit proc index, 28bit id, ,4bit cmd+flag
	int64_t msg_id = (val >> 4) & MaskBits(28);
	int proc_index = (val >> 32) & MaskBits(16);
	int socket_index = ((val) >> 48) & MaskBits(4);
	auto proc_rec(procs_.Get(proc_index));
	if (proc_rec.proc_.empty()) {
		return;
	}

	MQInfo dest = {proc_rec.ssn_ + socket_index, 0};
	auto FindMq = [&]() {
		auto pos = nodes_.find(proc_rec.ssn_);
		if (pos != nodes_.end()) {
			for (auto &&mq : pos->second->addrs_) {
				if (mq.first == dest.id_) {
					dest.offset_ = mq.second;
					return true;
				}
			}
		}
		return false;
	};
	if (!FindMq()) { return; }

	auto size = GetAllocSize((val >> 52) & MaskBits(8));
	MsgI new_msg;
	if (new_msg.Make(size)) {
		// 31bit proc index, 28bit id, ,4bit cmd+flag
		int64_t reply = (new_msg.Offset() << 32) | (msg_id << 4) | EncodeCmd(eCmdAllocReply0);
		SendAllocReply(socket, dest, reply, new_msg);
	} else {
		int64_t reply = (msg_id << 4) | EncodeCmd(eCmdAllocReply0); // send empty, ack failure.
		socket.Send(dest, reply);
	}
}

void NodeCenter::OnFree(ShmSocket &socket, const int64_t val)
{
	int64_t msg_id = (val >> 4) & MaskBits(31);
	msgs_.FreeMsg(msg_id);
}

bool NodeCenter::OnCommand(ShmSocket &socket, const int64_t val)
{
	assert(IsCmd(val));
	int cmd = DecodeCmd(val);
	switch (cmd) {
	case eCmdAllocRequest0: OnAlloc(socket, val); break;
	case eCmdFree: OnFree(socket, val); break;
	default: return false;
	}
	return true;
}

MsgProcInitReply NodeCenter::ProcInit(const BHMsgHead &head, MsgProcInit &msg)
{
	LOG_DEBUG() << "center got proc init.";
	auto pos = nodes_.find(head.ssn_id());
	if (pos == nodes_.end()) {
		return MakeReply<MsgProcInitReply>(eNotFound, "Node Not Initialised");
	}
	auto index = procs_.Put(head.proc_id(), head.ssn_id());
	auto reply(MakeReply<MsgProcInitReply>(eSuccess));
	reply.set_proc_index(index);

	auto &node = pos->second;
	try {
		for (int i = 0; i < msg.extra_mq_num(); ++i) {
			ShmSocket tmp(node->shm_, true, head.ssn_id() + i + 1, 16);
			node->addrs_.emplace(tmp.id(), tmp.AbsAddr());
			auto addr = reply.add_extra_mqs();
			addr->set_mq_id(tmp.id());
			addr->set_abs_addr(tmp.AbsAddr());
		}
		return reply;
	} catch (...) {
		LOG_ERROR() << "proc init create mq error";
		return MakeReply<MsgProcInitReply>(eError, "Create mq failed.");
	}
}

MsgCommonReply NodeCenter::Register(const BHMsgHead &head, MsgRegister &msg)
{
	if (msg.proc().proc_id() != head.proc_id()) {
		return MakeReply(eInvalidInput, "invalid proc id.");
	}

	try {
		MQId ssn = head.ssn_id();
		// when node restart, ssn will change,
		// and old node will be removed after timeout.
		auto pos = nodes_.find(ssn);
		if (pos == nodes_.end()) {
			return MakeReply(eInvalidInput, "invalid session.");
		}

		// try to remove old session
		auto old = online_node_addr_map_.find(head.proc_id());
		if (old != online_node_addr_map_.end()) { // old session
			auto &old_ssn = old->second;
			if (old_ssn != ssn) {
				nodes_[old_ssn]->PutOffline(offline_time_);

				LOG_DEBUG() << "put node (" << nodes_[old_ssn]->proc_.proc_id() << ") ssn (" << old->second << ") offline";
				old_ssn = ssn;
			}
		} else {
			online_node_addr_map_.emplace(head.proc_id(), ssn);
		}

		// update proc info
		Node &node = pos->second;
		node->proc_.Swap(msg.mutable_proc());
		node->state_.timestamp_ = head.timestamp();
		node->UpdateState(NowSec(), offline_time_, kill_time_);

		LOG_DEBUG() << "node (" << head.proc_id() << ") ssn (" << ssn << ")";

		return MakeReply(eSuccess);
	} catch (...) {
		return MakeReply(eError, "register node error.");
	}
}

MsgCommonReply NodeCenter::Unregister(const BHMsgHead &head, MsgUnregister &msg)
{
	return HandleMsg(
	    head, [&](Node node) -> MsgCommonReply {
		    NodeInfo &ni = *node;
		    ni.PutOffline(offline_time_);
		    return MakeReply(eSuccess);
	    });
}

MsgCommonReply NodeCenter::RegisterRPC(const BHMsgHead &head, MsgRegisterRPC &msg)
{
	return HandleMsg(
	    head, [&](Node node) -> MsgCommonReply {
		    auto src = SrcAddr(head);
		    auto &topics = msg.topics().topic_list();
		    node->services_[src].insert(topics.begin(), topics.end());
		    TopicDest dest = {src, SrcAbsAddr(head), node};
		    for (auto &topic : topics) {
			    service_map_[topic].insert(dest);
		    }
		    LOG_DEBUG() << "node " << node->proc_.proc_id() << " ssn " << node->addrs_.begin()->first << " serve " << topics.size() << " topics:\n";
		    for (auto &topic : topics) {
			    LOG_DEBUG() << "\t" << topic;
		    }
		    return MakeReply(eSuccess);
	    });
}

MsgCommonReply NodeCenter::Heartbeat(const BHMsgHead &head, const MsgHeartbeat &msg)
{
	return HandleMsg(head, [&](Node node) {
		NodeInfo &ni = *node;
		ni.state_.timestamp_ = head.timestamp();
		ni.UpdateState(NowSec(), offline_time_, kill_time_);

		auto &info = msg.proc();
		if (!info.public_info().empty()) {
			ni.proc_.set_public_info(info.public_info());
		}
		if (!info.private_info().empty()) {
			ni.proc_.set_private_info(info.private_info());
		}
		return MakeReply(eSuccess);
	});
}

MsgQueryProcReply NodeCenter::QueryProc(const std::string &proc_id)
{
	typedef MsgQueryProcReply Reply;
	auto Add1 = [](Reply &reply, Node node) {
		auto info = reply.add_proc_list();
		*info->mutable_proc() = node->proc_;
		info->mutable_proc()->clear_private_info();
		info->set_online(node->state_.flag_ == kStateNormal);
		for (auto &addr_topics : node->services_) {
			for (auto &topic : addr_topics.second) {
				info->mutable_topics()->add_topic_list(topic);
			}
		}
	};

	if (!proc_id.empty()) {
		auto pos = online_node_addr_map_.find(proc_id);
		if (pos == online_node_addr_map_.end()) {
			return MakeReply<Reply>(eNotFound, "proc not found.");
		} else {
			auto node_pos = nodes_.find(pos->second);
			if (node_pos == nodes_.end()) {
				return MakeReply<Reply>(eNotFound, "proc node not found.");
			} else {
				auto reply = MakeReply<Reply>(eSuccess);
				Add1(reply, node_pos->second);
				return reply;
			}
		}
	} else {
		Reply reply(MakeReply<Reply>(eSuccess));
		for (auto &kv : nodes_) {
			Add1(reply, kv.second);
		}
		return reply;
	}
}
MsgQueryProcReply NodeCenter::QueryProc(const BHMsgHead &head, const MsgQueryProc &req)
{
	typedef MsgQueryProcReply Reply;
	auto query = [&](Node self) -> Reply { return this->QueryProc(req.proc_id()); };
	return HandleMsg<Reply>(head, query);
}

MsgQueryTopicReply NodeCenter::QueryTopic(const BHMsgHead &head, const MsgQueryTopic &req)
{
	typedef MsgQueryTopicReply Reply;

	auto query = [&](Node self) -> Reply {
		auto pos = service_map_.find(req.topic());
		if (pos != service_map_.end() && !pos->second.empty()) {
			auto &clients = pos->second;
			Reply reply = MakeReply<Reply>(eSuccess);
			for (auto &dest : clients) {
				Node dest_node(dest.weak_node_.lock());
				if (dest_node && Valid(*dest_node)) {
					auto node_addr = reply.add_node_address();
					node_addr->set_proc_id(dest_node->proc_.proc_id());
					node_addr->mutable_addr()->set_mq_id(dest.mq_id_);
					node_addr->mutable_addr()->set_abs_addr(dest.mq_abs_addr_);
				}
			}
			return reply;
		} else {
			return MakeReply<Reply>(eNotFound, "topic server not found.");
		}
	};

	return HandleMsg<Reply>(head, query);
}

MsgCommonReply NodeCenter::Subscribe(const BHMsgHead &head, const MsgSubscribe &msg)
{
	return HandleMsg(head, [&](Node node) {
		auto src = SrcAddr(head);
		auto &topics = msg.topics().topic_list();
		node->subscriptions_[src].insert(topics.begin(), topics.end());
		TopicDest dest = {src, SrcAbsAddr(head), node};
		for (auto &topic : topics) {
			subscribe_map_[topic].insert(dest);
		}
		return MakeReply(eSuccess);
	});
}
MsgCommonReply NodeCenter::Unsubscribe(const BHMsgHead &head, const MsgUnsubscribe &msg)
{
	return HandleMsg(head, [&](Node node) {
		auto src = SrcAddr(head);
		auto pos = node->subscriptions_.find(src);

		auto RemoveSubTopicDestRecord = [this](const Topic &topic, const TopicDest &dest) {
			auto pos = subscribe_map_.find(topic);
			if (pos != subscribe_map_.end() &&
			    pos->second.erase(dest) != 0 &&
			    pos->second.empty()) {
				subscribe_map_.erase(pos);
			}
		};

		if (pos != node->subscriptions_.end()) {
			const TopicDest &dest = {src, SrcAbsAddr(head), node};
			auto &topics = msg.topics().topic_list();
			// clear node sub records;
			for (auto &topic : topics) {
				pos->second.erase(topic);
				RemoveSubTopicDestRecord(topic, dest);
			}
			if (pos->second.empty()) {
				node->subscriptions_.erase(pos);
			}
		}
		return MakeReply(eSuccess);
	});
}

NodeCenter::Clients NodeCenter::DoFindClients(const std::string &topic)
{
	Clients dests;
	auto Find1 = [&](const std::string &exact) {
		auto pos = subscribe_map_.find(exact);
		if (pos != subscribe_map_.end()) {
			auto &clients = pos->second;
			for (auto &cli : clients) {
				if (Valid(cli.weak_node_)) {
					dests.insert(cli);
				}
			}
		}
	};
	Find1(topic);

	size_t pos = 0;
	while (true) {
		pos = topic.find(kTopicSep, pos);
		if (pos == topic.npos || ++pos == topic.size()) {
			// Find1(std::string()); // sub all.
			break;
		} else {
			Find1(topic.substr(0, pos - 1));
		}
	}
	return dests;
}

bool NodeCenter::FindClients(const BHMsgHead &head, const MsgPublish &msg, Clients &out, MsgCommonReply &reply)
{
	bool ret = false;
	HandleMsg(head, [&](Node node) {
		DoFindClients(msg.topic()).swap(out);
		ret = true;
		return MakeReply(eSuccess);
	}).Swap(&reply);
	return ret;
}

void NodeCenter::OnTimer()
{
	CheckNodes();
	msgs_.AutoRemove();
}

void NodeCenter::CheckNodes()
{
	auto now = NowSec();
	if (now <= last_check_time_) { return; }
	last_check_time_ = now;

	auto it = nodes_.begin();
	while (it != nodes_.end()) {
		auto &cli = *it->second;
		cli.UpdateState(now, offline_time_, kill_time_);
		if (cli.state_.flag_ == kStateKillme) {
			RemoveNode(it->second);
			it = nodes_.erase(it);
		} else {
			++it;
		}
	}
	msgs_.DebugPrint();
}

void NodeCenter::RemoveNode(Node &node)
{
	auto EraseMapRec = [&node](auto &rec_map, auto &node_rec) {
		for (auto &addr_topics : node_rec) {
			TopicDest dest{addr_topics.first, 0, node}; // abs_addr is not used.
			for (auto &topic : addr_topics.second) {
				auto pos = rec_map.find(topic);
				if (pos != rec_map.end()) {
					pos->second.erase(dest);
					if (pos->second.empty()) {
						rec_map.erase(pos);
					}
				}
			}
		}
	};
	EraseMapRec(service_map_, node->services_);
	EraseMapRec(subscribe_map_, node->subscriptions_);

	// remove online record.
	auto pos = online_node_addr_map_.find(node->proc_.proc_id());
	if (pos != online_node_addr_map_.end()) {
		if (node->addrs_.find(pos->second) != node->addrs_.end()) {
			online_node_addr_map_.erase(pos);
		}
	}

	for (auto &addr : node->addrs_) {
		auto &id = addr.first;
		auto r = ShmSocket::Remove(node->shm_, id);
		LOG_DEBUG() << "remove mq " << id << (r ? " ok" : " failed");
	}

	node->addrs_.clear();
}

void NodeCenter::Publish(SharedMemory &shm, const Topic &topic, const std::string &content)
{
	try {
		// LOG_DEBUG() << "center publish: " << topic << ": " << content;
		Clients clients(DoFindClients(topic));
		if (clients.empty()) { return; }

		MsgPublish pub;
		pub.set_topic(topic);
		pub.set_data(content);
		BHMsgHead head(InitMsgHead(GetType(pub), id(), 0));
		MsgI msg;
		if (msg.Make(head, pub)) {
			DEFER1(msg.Release());
			RecordMsg(msg);

			auto &mq = GetCenterInfo(shm)->mq_sender_;
			ShmSocket sender(mq.offset_, shm, mq.id_);

			for (auto &cli : clients) {
				auto node = cli.weak_node_.lock();
				if (node && node->state_.flag_ == kStateNormal) {
					sender.Send({cli.mq_id_, cli.mq_abs_addr_}, msg);
				}
			}
		}

	} catch (...) {
		LOG_ERROR() << "center publish error.";
	}
}